A n00b/noob is that annoying fat kid on xbox live that is yelling at everyone through the crappy mic and ends up with the lowest kill in the history of man, they are the ones that mess up a good match by teamkilling with flamethrowers or making your team lose the match by 1 point because they accidently walked off the edge of a cliff. Usually aged 8-14 and have nothing better to do than attempting internet greatness through the exessive and pointless use of crap lolcat pictures and animations that are so over used it makes you want to vomit (ps: i love lolcats with a passion but i am referring to the ones for example the cat with a sniper rather than the funny intellegent pictures)
n00b = suckish

1) A person who is new to a game
2) A person who, regardless of experience, lacks the skill or copmetence to be competitive in a certain game
3) Someone who tends to whine or complain when being beaten at a game - often done by accussing more skilled opponents of hacking
4) One who may talk trash, claiming to be elite at a game, only to be beaten down by a better player, or will turn down any games when challenged by better players.

v.

1) To act or behave in the way that a n00b would
2) Behaving as if lacking experience, skill or knowledge

NOTE: Can be used with a number of connotations. Often is used mockingly or in a manner of jesting. Other times is used seriously, but is often considered a brainless or weak insult when used alone as a supposed malicious insult. Is generally considered rude and deragatory unless a person is displaying disregard and general apathy towards other players - in this case, skill may be a non-factor (see definitions 3 and 4).

An individual that plays a particular multiplayer game less than 15 hours a day, thus causing him/her to be less skilled at that game than the person calling him/her a n00b. N00bs are usually classified as having a job, an active social life, and possibly a lover. These things are reviled in the "gamer" community, which means that n00bs are hated with a passion in thier circles. The term is usually used in Counterstrike servers and Battle.net, where many mouthbreathing "elite gamers" and internet tough-guys can be found.

A player who may or may not be new to a game, but insists on doing brainless things, especially things that hinder the team. Those who are defined as "n00bs" will also refuse to listen to words of wisdom or, even worse, berate those who try to help.